Continuously variable automatic transmissions, hereinafter designated as CVT, consist of the following units: starting unit, forward/reverse drive unit, variator, intermediate shaft and differential. Such CVT's are usually driven by an internal combustion engine, via an input shaft, such as a crankshaft. As starting unit serves either a starting clutch or a hydrodynamic converter. The forward/reverse drive unit serves for the reversal of direction of rotation of the input shaft for the reverse drive. The forward/reverse drive unit is mostly designed as a planetary reversing gear. The latter consists of at least one sun gear, several planets, one ring gear, one brake and one clutch of multi-disc design. The variator consists of two pairs of cone pulleys and one belt. Each pair of cone pulleys, in turn, consists of one first cone pulley half stationary in its axial direction and one second cone pulley movable in axial direction. The belt, such as a thrust link conveyor, extends between the pairs of cone pulley halves. By the adjustment of the second cone pulley half the drive radius of the belt and thus the ratio of the CVT is adjusted.
A CVT, having a forward/reverse driver unit, was made known in the Automobiltechnischen Zeitschrift 96 (1994) 6, page 380, FIG. 3. Here a first shaft driven by the impeller of the hydrodynamic converter drives planetary gears connected by a common first planet spider. Each planetary gear is rotatably mounted upon a stud. On the one hand, the planetary gears mesh with a sun gear located upon a second shaft and, on the other hand, with a ring gear. By a brake of a multi-disc design, the ring gear can be fixed against a stationary wall such as the transmission housing. The second planet spider is connected by a clutch of the multi-disc design with the first cone pulley. When the clutch is closed, the planetary reverse gear revolves as a whole with the ratio of 1 and the same direction of rotation as the first shaft. When the brake is closed, a reversal of direction of rotation for the reverse drive takes place. The gears of the planetary reverse gear are usually helical. Due to the helical teeth of the planet/ring gear, axial forces appear on the ring gear. According to the cited prior art, the ring gear is supported in an axial direction either on the second planet spider connected with the clutch or on the stationary wall.
The problem on which the present invention is based is to further develop a brake having its internal disc carrier connected with a ring gear.